Make Crumb Topping
Combine flour, sugars, and cinnamon. Add melted butter and mix until crumbly.
Make Cinnamon Swirl
Combine flour, sugar, and cinnamon.
Make Glaze (Optional)
Combine glaze ingredients.
Prepare Batter
Whisk flour, brown sugar, baking powder, baking soda, cinnamon, and salt.
Whisk eggs, milk, butter, and vanilla.
Pour wet into dry ingredients and mix until smooth batter.
Bake Muffins
Preheat oven to 375 degrees. Line muffin tin.
Fill each muffin cup with 2 tablespoons of batter.
Add 1 teaspoon of cinnamon swirl mixture to each. Swirl into batter.
Top with more batter, filling ¾ full.
Top with 1 ½ tablespoons of crumb topping.
Bake 15-17 minutes.
Cool in pan, then on wire rack.
Drizzle with glaze, if using.
